The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In wells employing multistage hydraulic fracturing stage tools, a fracturing port is usually opened by sliding a sleeve, permitting injected fracturing fluids to escape the wellbore and create a fracture in the surrounding formation. The device that shifts the sleeve is a ball, a dart, or even a length of tubing inserted into the wellbore. The device travels (or is inserted) up to the point where the device is captured by a capture feature on the stage tool, such as a collet, lever, cavity, etc., and further device motion pushes the sleeve open. Some representative multistage hydraulic fracturing stage tools are disclosed in U.S. Pat. Nos. 7,387,165, 7,322,417, 7,377,321, US20070107908, US20070044958, US20100209288, U.S. Pat. No. 7,387,165, US2009/0084553, U.S. Pat. Nos. 7,108,067, 7,431,091, 6,907,936, 7,543,634, 7,134,505, 7,021,384, 7,353,878, 7,267,172, 7,681,645, 7,703,510, 7,784,543, 7,628,210, WO2012083047, U.S. Pat. Nos. 7,066,265, 7,168,494, 7,353,879, 7,093,664, 7,210,533, 7,343,975, 7,431,090, 7,571,766, 8,104,539, and US2010/0044041, U.S. Pat. Nos. 8,066,069, 6,866,100, 8,201,631; US20120090847; US20110198082; US20080264636, which are hereby incorporated herein by reference.
Fracturing is used to increase permeability of subterranean formations. A fracturing fluid is injected into the wellbore passing through the subterranean formation. A propping agent (proppant) is injected into the fracture to prevent fracture closing and, thereby, to provide improved extraction of extractive fluids, such as oil, gas or water.
The proppant maintains the distance between the fracture walls in order to create conductive channels in the formation. It is known that heterogeneous placement through pulsing of proppant enable to create pillars improving the conductivity of the fracture and thus enabling a higher productivity of the wells; however, such a process is generally difficult to control when involving multistage completion tools.
Such multistage tools enable a reduction of non-productive time and thus the industry would welcome a system enabling the formation of pillars and/or cluster when using multistage completion tools.